Gallium nitride materials include gallium nitride (GaN) and its alloys such as aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), and aluminum indium gallium nitride (AlInGaN). These materials are semiconductor compounds that have a relatively wide, direct bandgap which permits highly energetic electronic transitions to occur. Such electronic transitions can result in gallium nitride materials having a number of attractive properties including the ability to efficiently emit blue light, the ability to transmit signals at high frequency, and others. Accordingly, gallium nitride materials are being widely investigated in many semiconductor device applications such as transistors, field emitters, and optoelectronic devices.
Gallium nitride materials have been formed on a number of different substrates including silicon carbide (SiC), sapphire, and silicon. Device structures, such as doped regions, may then be formed within the gallium nitride material region. In certain device applications, heat is generated as a result of resistance to current flow within the device. In particular, active device areas and/or highly resistive regions may generate large amounts of localized heat. The excessive heat may damage the device or cause performance problems. Therefore, it is desirable to distribute and/or dissipate heat generated within the device.
Certain substrates, such as SiC, are relatively good thermal conductors which can facilitate heat distribution and/or dissipation during device operation. However, silicon only moderately conducts heat. Therefore, heat generally is not efficiently distributed or dissipated through silicon substrates.